619. Co-Expression of AAV Mediated Angiopoietin-1 and VEGF in Ischemic Hearts Yield Leakage-Resistant Blood Vessels and Better Therapeutic Effect Than VEGF Alone

Abstract

Top of pageAbstract Previously, we have shown that vascular endothelial growth factor (VEGF) gene delivered by adeno-associated viral vector (AAV) into ischemic myocardium could induce neoangiogenesis and improve cardiac function. It has been reported that in the skin of transgenic mice, blood vessels induced by over-expressing VEGF were leaky, whereas blood vessels induced by over-expression of angiopoietin-1 were not. Co-expression of angiopoietin-1 and VEGF had also an additive effect on angiogenesis in addition to producing leakage-resistant vessels. Because of these reports, we investigated whether in ischemic hearts the new blood vessels induced by AAV mediated VEGF gene expression are leaky and if the addition of angiopoietin-1 can prevent the leakiness and improve the therapeutic effect of VEGF. We constructed two AAV vectors, AAV-VEGF and AAV-ang-1 with CMV promoter driving VEGF or angiopoietin-1 gene expression. These two vectors were injected to mouse ischemic hearts individually or together in different ratios. Mice injected with AAV-LacZ vector or HEPES buffer were used as control. Cardiac function was investigated by echocardiogram four weeks after the vector injection. To study the leakiness of blood vessels, Evans blue was injected into the femoral veins after the mice were anesthetized. Hearts were fixed by perfusion with paraformaldehyde and the left ventricles were dissected out. The Evans blue that leaked out from blood vessels was extracted from the hearts with formamide and measured with a spectrophotometer. All the treated groups had better cardiac function than the AAV-LacZ and HEPES buffer injected control groups. AAV-ang-1 injected mice have less leaky blood vessels than AAV-VEGF injected mice, and similar cardiac function as AAV-VEGF injected mice. The mice that received co-injection of AAV-VEGF and AAV-ang-1 in 1:1 ratio showed the best cardiac function among all the animals. Co-injection of AAV-ang-1 and AAV-VEGF also reduced blood vessel leakage cause by AAV-VEGF injection. We conclude that co-expression of angiopoietin-1 with VEGF results in the formation of new blood vessels that are leak resistant, and cardiac function that is better than mediated by AAV-VEGF or AAV-ang-1 alone.